"Smart" ads

I confess to a certain fascination with the ads that Google AdSense picks to complement my blog pages. Sometimes they're so "smart" it's a bit spooky. I just found this one on my home page:

NMR Magnet Sales
Oxford – Spectro Spin - Varian Ranging from 100 - 600 Mhz
www.mrr.com

I can only assume this must be loosely related to my post about interviewing for a chemistry job. A previous ad (which I failed to copy) was specifically about answering interview questions. I'd love to know how the software makes associations. I mean, I can see it coming up with general "job-hunting" or "interview"-related sites, but this was much more specific to the post content. And that post didn't say anything about NMR at all, but it's the only one that could be the source.

Do you suppose blogging about the ad service will result in an ad about the service?